The present invention relates generally to an instrument panel used in a vehicle having a supplemental inflatable restraint (SIR) system, and more particularly to an instrument panel cover having an integral hidden door and the method of manufacture thereof.
As more and more vehicles are equipped with SIR systems, other vehicle components have been modified to accommodate the use of such systems. For example, most passenger side SIR systems are disposed within and behind an instrument panel which extends across the width of a vehicle compartment. During assembly, a conventional instrument panel in a vehicle having a passenger side SIR system requires a discrete door which covers an opening formed in the instrument panel for the air bag cushion to deploy through upon actuation of the SIR system. This separate door is designed to open in response to the force of the expanding air bag cushion. In other words as the pressure in the air bag cushion increases, a force is generated and as the air bag cushion deploys at this force, the door selectively separates from the remaining portion of the instrument panel to permit the air bag cushion to deploy.
Typically, the manufacture of the conventional instrument panel involves forming an opening in the instrument panel adjacent to the SIR system. This opening is then covered by a separate door which is secured to the instrument panel and faces the occupants of the vehicle. Thus, the instrument panel itself is manufactured in view of the shape and size of the door and the door is separately manufactured and installed in the instrument panel using known techniques.
Due to ongoing desires for decreasing the weight of the vehicle compartment and improving the aesthetics of the passenger compartment, it is desirable to provide aesthetically pleasing, functional alternatives to the conventional instrument panels having a separate door covering the SIR system.
According to the present invention, an instrument panel having a hidden deployment region integrally formed within an inner surface of an instrument panel cover by an ultrasonic embossing process is provided. More specifically, the deployment region comprises at least one and preferably a plurality of scores or cuts formed in the inner surface of the instrument panel cover according to a predetermined pattern. The scores represent weakened portions of the instrument panel cover designed so that the force of an inflating air bag cushion causes the instrument panel cover to separate along the scores to thereby provide an opening for the inflating air bag cushion to deploy therethrough and be directed into the passenger compartment of a vehicle. The deployment region may be defined by any number of scores and therefore may have a variety of patterns, including but not limited to xe2x80x9cHxe2x80x9d pattern, xe2x80x9cUxe2x80x9d pattern, and xe2x80x9cIxe2x80x9d pattern.
Because the scores defining the deployment region are formed on the inner surface of the instrument panel cover, the present invention advantageously eliminates the use of components and processes involved with the manufacture of separate passenger air bag doors. By eliminating the need for a separate door, the hidden deployment region of the present invention has no markings or seams on an outer surface of the instrument panel cover which faces the occupants of the vehicle. In other words, the hidden deployment region is completely concealed from observation by the occupants and permits the outer surface of the instrument panel cover to have a stylistically uniform appearance.
The ultrasonic embossing process of the present invention utilizes at least one blade contoured to the size and shape of the periphery of the deployment region through which the air bag must pass during deployment. The at least one blade is oscillated at an ultrasonic frequency as it is advanced into the inner surface of the instrument panel cover to make a very precise cut or score. The depth of this score is controlled very precisely such that the at least one blade will move within a given distance of the outer surface of the instrument panel cover. The oscillating blade effectively heats and melts the instrument panel cover material at the inner surface to form a given score. By precisely controlling the depth of the score(s), the thickness of the remaining unscored material may be controlled and this is important because it the remaining unscored material thickness which determines the force required for the deployment region to separate along the score(s) to permit the air bag cushion to properly deploy therethrough. When the air bag cushion begins to inflate and build pressure therein, the force of the air bag cushion against the inner surface causes the score(s) defining the periphery of the deployment region to tear or separate to form an opening for the air bag cushion to pass therethrough.
The ultrasonic embossing process and instrument panel cover of the present invention provides for a reduction of manufacturing and assembly costs and for a reduction in assembly time and complexity by providing a simple, effective process for forming a hidden deployment region in the instrument panel cover. Cost savings are realized due to the elimination of the components and processes involved within the manufacture and assembly of separate passenger air bag doors which are installed within the instrument panel cover.
The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.